This invention is related to a device for relative movement of two elements, one of which forms a base element whereas a second is movable relative to the base element, comprising at least two link devices coupled between the elements, said link devices each comprising at least two mutually articulated link units, and power exerting arrangements adapted to cause the link devices to pivot for changing the relative position of the elements, a first of the link devices being connected to one of the elements via a hinge connection so that there are, on consideration of the device in its entirety, at least two degrees of freedom between said first link device and said element in the form of relative pivotability about two pivot axes, real or imaginary, placed at an angle relative to each other.
The relative movement of the two elements has the purpose to position them mutually in a manner aimed at by means of the power exerting arrangements. More specifically, the device according to the invention is intended to form a manipulator or robot. The moveable of the elements is intended to carry, directly or indirectly via a carrying arrangement, a working member to execute the function aimed at.
A robot is described in U.S. Pat. No. 4,976,582. For the positioning of the second element, the known robot comprises three power exerting arrangements, which comprise three power exerting members arranged in a triangular distribution on the first element. Each of the power members is connected to the moveable second element via its own connection comprising a link device each comprising at least two mutually articulated link units. First link units hingedly connected to the first link unit and to the second element respectively via connections providing, on consideration of the device in its entirety, two degrees of freedom.
A disadvantage with this known type of robot is that it becomes comparatively bulky as a consequence of the triangular distribution discussed herein above. Furthermore, it is structurally difficult to design the known robot with the required flexibility concerning working area and movement area since the first link units project in a star shaped manner from the first element.
The invention primarily aims at devising routes to develop the device of the kind defined by way of introduction so as to eliminate or at least reduce one or more of the disadvantages mentioned herein above, a particular aim being to provide a great flexibility as to the design of the device and an optimum of working area for the device. It is secondarily aimed at to devise routes to realise, in a rational and uncomplicated manner, transmission of movements from the base element to the moveable element.
As far as the primary aspect of the invention is concerned, the object presented is achieved by a further of the link devices being connected to another of the elements via a hinge connection which, on consideration of the device in its entirety, provide for freedom of movement between said further link device and said another of the elements in respect to at least two degrees of freedom consisting of pivotability about two different pivot axes, real or imaginary.
In this way conditions are created for a more flexible working area adaptation of the device. Furthermore, the solution defined creates possibilities to construct the device so that one of the link devices could be connected to, in the first instance, the base element via said hinge connection so that the movement of the link device at least in part becomes dependent on the movement of at least one other link device. This involves a difference relative to the device according to the U.S. Pat. No. 4,976,582 where the three link devices are functionally independent of each other.
A number of advantageous developments of the invention are defined in the dependent claims. These developments and advantages in connection with the invention are dealt with more specifically in the following description.